An explanation of the plants used in this site...
 

Amanita muscaria (Fly Agaric), seminars

The Fly Agaric is a source of muscimol,  thought to have psychotropic activity.  Muscimol is an agonist at GABAA receptors which transmit inhibitory signals in the brain.  This mushroom also is a source of muscarine, the drug that defined the muscarinic acetylcholine receptor, important for the parasympathetic control of most organs of the body.

Atropa belladonna (Deadly Nightshade), homepage

Atropine, one of the most important pharmaceuticals ever discovered, is derived from the Deadly Nightshade.  It was named for the Greek Atropos, one of the Fates that cut the threads of human life.  Belladonna refers to the Italian women who would use deadly nightshade to "brighten" their eyes by dilating the pupils.  It does this by antagonizing the action of acetylcholine at muscarinic acetylcholine receptors.

Erythroxylon coca (Coca), info for students page

Coca is the plant that is used to produce cocaine, an historic anesthetic and drug of addiction.  Cocaine is thought to act mainly by inhibiting the uptake of synaptically released dopamine into nerve terminals, thus prolonging the synaptic effects of this neurotransmitter.

Nicotiana tabacum (Tobacco), faculty page

Tobacco is a major agricultural product grown throughout the world.  Since the colonization of North America tobacco has become one of the world's largest and most lucrative harvests.  Tobacco leaves are the source of the drug nicotine whose specific action to stimulate the nicotinic acetylcholine receptors found in striated muscle, autonomic ganglia, and the CNS,  gave them their name.

Papaver somniferum (Opium Poppy),  courses page

Opium, named for the Greek word opos, meaning juice, is derived from the seed pod of the Opium Poppy.  Morphine and codeine, two drugs widely used to control pain, are derived from the opium poppy.  These drugs are agonists at various opioid receptors in the brain.

Physostigma venenosum (Calabar Bean), admissions page

The calabar bean comes from Old Calabar, West Africa where it is known as the Ordeal Bean.  The beans were used by natives as a test of innocence or guilt; the guilty would die after injesting the bean.  The calabar bean is used to produce the toxin physostigmine, a very useful tool in modern day science.  Physostigmine acts as an inhibitor of acetylcholinesterase, the enzyme that terminates the synaptic action of acetylcholine.  By inhibiting the enzyme, the action of acetylcholine is prolonged.

Strychnos ignatii (St. Ignatius bean), courses page

The St. Ignatius Bean is native to the Phillipines, but was named for Jesuits in Cochin China that studied this plant.  At one time, it was thought that the Strychnos species could be used to treat cholera.  Its importance to Pharmacology is the chemical derivative, strychnine.  Strychnine was discovered in 1818 by French Chemists Joseph-Bienaime Caenoin and Pierre-Joseph Pelletier, and is still in use today.  Strychnine is an antagonist of the actions of glycine which is a major inhibitory neurotransmitter in the brain.

Information taken from:

 http://botanical.com, a modern herbal guide
http://bltc.com, a site dedicated to paradise-engineering
http://www.thinkquest.org, poisonous plants and animals website
http://www.lycaeum.org/

Other informative botanical links:

The Urban Herb, a guide to the plantlife around campus (sponsored by CAM)